A general touch sensor device has a plurality of separate input/output (I/O) terminals for receiving an input generated by external touch, driving an externally arranged light-emitting device such as a light emitting diode (LED), and communicating to external control device
FIG. 1 is a block diagram showing a configuration of a conventional touch sensor device.
A touch sensor device 101 comprises a light-emitting device driver 125, a touch sensor 130, and a controller 135. In addition, the touch sensor device further comprises a plurality of output terminals 161-3 to 16N-3 for outputting a signal to external light-emitting devices 150 to 15N, and a plurality of I/O terminals 181 to 18N for receiving and outputting a signal from/to an external contact unit 170.
The contact unit 170 arranged adjacent to one side of the touch sensor device 101 has a plurality of typical contact pads 171 to 17N, and a light-emitting unit 140 arranged adjacent to another side of the touch sensor device 101 has a plurality of light-emitting devices 150 to 15N having LEDs 150-1 to 15N-1 and resistors 150-2 to 15N-2.
Functions of the respective blocks shown in FIG. 1 will now be described below.
In response to signals output from the contact pads 171 to 17N, the touch sensor 130 generates and outputs a touch detection signal touch_info to the controller 135.
In response to the touch detection signal touch_info output from the touch sensor 130, the controller 135 outputs a control signal for driving the corresponding light-emitting device to the light-emitting device driver 125 and communicating to external control device 150.
The LEDs 150-1 to 15N-1 of the light-emitting unit 140 are controlled by a control signal output from the light-emitting device driver 125. The control signal is output according to a combination of signals sig1 to sigN respectively output from the contact pads 171 to 17N. For example, the touch detection signal touch_info is generated by the touch sensor 130 in response to the signal sig1 output from the contact pad 171, a predetermined current is applied to the LED 150-1 in response to the touch detection signal touch_info, and thus the LED 150-1 is turned on.
The number of the externally arranged contact pads 171 to 17N is determined according to the number of inputs that must be applied by touch. For example, an input unit for controlling functions of a specific electronic device must have a plurality of contact pads according to the number of required inputs. With the trend of electronic devices to have high quality and high performance, the number of functions to be controlled is increasing together with the number of the contact pads 171 to 17N for processing an input generated by external touch.
Here, when input is performed through contact pads, some electronic devices may inform a user that input is being performed. In the case of a general cellular phone, when input is performed through contact pads for making a phone call, inner LEDs are driven to notify a user that input is being performed.
Conventionally, with an increase in the number of contact pads, the number of light-emitting devices having connected LEDs also increases. Thus, in the touch sensor device 101 of FIG. 1, the number of the I/O terminals 181 to 18N and the number of the output terminals 161-3 to 16N-3 must increase. However, since the number of I/O terminals of the touch sensor device 101 is limited, the numbers of external contact pads and light-emitting devices that can be connected to the I/O terminals also are limited.
Therefore, a new touch sensor device is necessary which performs the same operation while having a reduced number of I/O terminals by improving a touch sensor device structure.